The present invention relates to packaging semiconductor devices, and more particularly to packaging board on chip (BOC) devices.
The semiconductor technology has shown a general trend towards the dramatic increase in integrated circuit speed and density. Both of these trends are fueled by a general reduction in device (active element) geometries. As semiconductor devices becomes smaller, the distances between them on a semiconductor die become, and parasitics (such as parasitic capacitances) and switching currents become smaller. In technologies, such as CMOS, where overall current draw and switching speed characteristics are dominated by the effects of parasitics, the result is a reduction in total power consumption at the same time as switching speed is improved. Overall speed is further improved by the reduction in signal propagation time between active devices (e.g., transistors), resulting from the shorter distances involved. In today""s high speed integrated circuitry based on sub-micron geometries, delays in the tens or hundreds of picoseconds can be appreciable.
Typically, integrated circuit dies (chips, or semiconductor dies) are diced (cut apart, or singulated) from a semiconductor wafer and are separated into integrated circuit packages which have pins, leads, solder (ball) bumps, or conductive pads by which electrical connections may be made from external systems to the integrated circuit chip. These packages are then typically applied to circuit board assemblies including systems of interconnected integrated circuit chips.
The aforementioned dramatic improvements in integrated circuit speed and density have placed new demands on integrated circuit assemblies, both at the chip and circuit board levels. Without attendant improvements in these areas, much of the benefit of high device speed is lost. Wiring propagation delays and transmission line effects, in integrated circuit packages and on circuit board assemblies, which were once negligible are now significant factors in the overall performance of systems based on high-speed integrated circuitry. In order to achieve the potential higher system level performance opportunities afforded by the new high density technologies, it is necessary to reduce the amount of signal propagation time between integrated circuits.
Another significant factor in achieving high system level performance is signal drive capability. Longer signal paths are susceptible to noise, cross-talk, etc., and require low impedance, high current drive circuits on the integrated circuit chips (dies). Such circuits tend to occupy large portions of the die area, either reducing the area available for other circuitry or increasing the overall die size, and can introduce significant delays of their own. Clearly, shorter signal paths and their attendant low signal drive current requirements are desirable to achieve high performance.
In the prior art, a number of high density chip assemblies and packages have been proposed and implemented. One such technique is commonly known as xe2x80x9cchip-on-boardxe2x80x9d technology, whereby integrated circuit dies are bonded directly to die mounting areas on a circuit board substrate, for example, ceramic, fiberglass, etc., and are wire bonded (with thin xe2x80x9cbond wiresxe2x80x9d) to traces on the circuit board in areas adjacent to the edges of the dies. The elimination of the traditional integrated circuit package permits chips to be placed much closer together than would otherwise be possible, thereby shortening signal paths and reducing delays.
The present invention reduces inductance that is induced between wires and internal leads. Additionally, the present packaging arrangement provides one package for all applications. The package for the present invention provides short traces leading to favorable impedance coupling. These short wires are designed to reduce electrical impedance important for the operation of high speed devices, such as the synchronous DRAM. Additionally, the present invention eliminates wire shorts to the bus bar and eliminates T/F. Additionally, the present invention eliminates the use of ultra-advance molding equipment development. Additionally, the present invention provides a true chip size package, which leads to improved mapping density. Additionally, the present invention eliminates the bent leads. Lastly, the present invention eliminate noise due to cross-talk and improves the delays associated with longer wires.
The present invention includes a package for an integrated circuit, including a circuit board for mounting the integrated circuit having a first surface and a second surface, a connector device positioned on the first surface of the circuit board for electrically connecting the integrated circuit, and the integrated circuit being positioned on the second surface.